Justice League of America Vol 1 4

""Doom of the Star Diamond!"": Returning from a mission in space, Carthan of Dryanna learns that his ruler Xandor wishes to exile him because as the planets greatest hero, he may lead a revolt to usurp his command. Unable to kill Carthan because of a protective aura about him he is instead exile

Synopsis for "Doom of the Star Diamond!"

Returning from a mission in space, Carthan of Dryanna learns that his ruler Xandor wishes to exile him because as the planets greatest hero, he may lead a revolt to usurp his command. Unable to kill Carthan because of a protective aura about him he is instead exiled to Earth. Knowing of the Justice League, Carthan is unable to contact them telepathically, however believes he can trick them into helping him stop Xandor if he pretends to be evil.

As the Justice League of America considers who will be the next super-hero inducted into their ranks, Carthan sends a arrow with a message telling them of ultra weapons which will destroy the Earth if the Justice League does not stop them. The JLA decides to split up into groups and tackle the problem head on.

Martian Manhunter and Wonder Woman seek the first doomsday weapon in Keystone City, and have to battle giant insects and birds that have been mutated by the weapon. Defeating their attackers, they succeed in covering the device with a metal sheet. While Flash and Aquaman race to Australia where they have to search for the device with the help of Aquaman's undersea friends. After locating the device, the Flash's super speed helps raise the control lever on the device for Aquaman to shut down. And finally, Green Lantern tackles the last device located near Italy, battling aliens that are protected by yellow, he uses his power ring to creatue petrified wood around them before shutting off the machine he finds.

While this is going on, Superman and Batman have located Carthan's ship, and the two heroes board and find that Green Arrow is Carthan's prisoner. Also, Carthan has captured the other JLA members and imprisoned them in a giant crystal. However, before Carthan can explain his situation, Superman, Batman and Green Arrow attack damaging the device trapping the JLA members in the device. Using a diamond tipped arrow, Green Arrow manages to destroy the diamond prison that is holding the other heroes. After hearing Carthan's story, the JLA offer to aid him in overthrowing Xandor, however Carthan declines stating that it is his own fight. Returning to their headquarters, the JLA nominates Green Arrow as their newest member.